| Age differences in knee extension power, contractile velocity, and fatigability. | |
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MedLine Citation:
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PMID: 15347625 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The purposes of this study were to examine age and gender differences in knee extensor strength, power, and fatigue using open- and closed-chain testing procedures. We tested the hypothesis that specific strength (strength/unit muscle mass) would not differ by age, whereas age differences in specific power and fatigue would remain consequent to blunted maximal contractile velocity. Skeletal muscle performance was examined in 28 young (26.9 +/- 0.7 yr) and 24 older (63.6 +/- 0.8 yr) men and women. Assessments included one-repetition maximum strength for knee extension, leg press, and squat; concentric knee extensor peak power, velocity, and fatigability; and sit-to-stand power, fatigability, and relative neural activation (electromyograph activity during sit-to-stand movement normalized to electromyograph activity during isometric maximum voluntary contraction). Thigh lean mass (TLM; kg) was assessed by dual-energy X-ray absorptiometry. Specific strength (N/kg TLM) and specific power (W/kg TLM) were estimated by dividing absolute values by TLM. Age differences in specific strength were observed for knee extension only (young, 41.2 +/- 1.0 N/kg TLM; older, 32.4 +/- 1.0 N/kg TLM; P < 0.05). Adjustment for TLM did not negate age differences in knee extension specific power (25-41% lower in older; P < 0.05) across loads tested. Older adults experienced fatigue across 10 repetitions of knee extension as peak velocity fell by 24% (P < 0.05). Deficits in concentric power persist after adjustment for TLM as maximum contractile velocity falls markedly with aging. Older adults are less capable of sustaining maximum concentric velocity during repetitive contractions. These findings suggest that velocity impairments are a possible contributor to mobility loss and falls risk among older adults. Interventions for improving contractile velocity should be pursued. |
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Authors:
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John K Petrella; Jeong-su Kim; S Craig Tuggle; Samuel R Hall; Marcas M Bamman |
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Publication Detail:
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Type: Clinical Trial; Journal Article; Research Support, U.S. Gov't, P.H.S. Date: 2004-09-03 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 98 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2005 Jan |
Date Detail:
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Created Date: 2004-12-13 Completed Date: 2005-05-11 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 211-20 Citation Subset: IM |
Affiliation:
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Muscle Research Laboratory, UAB Dept. of Physiology and Biophysics, University of Alabama at Birmingham, and GRECC/11G VA Medical Center, 1530 3rd Avenue South, Birmingham, AL 35294-0001, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Age Factors Aged Aging / physiology* Female Humans Knee / physiology* Male Middle Aged Movement / physiology* Muscle Contraction / physiology* Muscle Fatigue / physiology* Physical Endurance / physiology* Sex Factors |
| Grant Support | |
ID/Acronym/Agency:
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M01 RR 00032/RR/NCRR NIH HHS; R01 AG 17896/AG/NIA NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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